5. Air loss may play role in lowering of an Antarctic ice shelf
The surface elevation of the Larsen Ice Shelf in the Antarctic Peninsula has lowered by about 0.1 meters per year (3.9 inches per year) since 1992. This could be caused either by an increase in the density of firn (compacted snow) at the surface of the ice shelf or by an increase in melting of ice at the base of the ice shelf. Attributing the observed lowering to one of these causes would help researchers to know whether atmospheric or ocean warming was impacting the ice shelf. To do this, it is necessary to know the density or air content of the firn. However, firn air content has been measurable only with labor-intensive ground-based techniques.
To overcome those challenges, Holland et al. developed a new method that uses radar sounding measurements to estimate air content. Using their method, the authors observe spatial variations in the air content of the shelf. Overall, they find that the air content suggests that loss of air (increased firn density) could account for the observed lowering of the surface of the ice shelf, though the result does not rule out a contribution from melting at the base of the ice shelf.
Geophysical Research Letters, doi:10.1029/2011GL047245, 2011
Title: The air content of Larsen Ice Shelf
Authors: Paul R. Holland, Hugh F. J. Corr, Hamish D. Pritchard, David G. Vaughan, Robert J. Arthern, and Adrian Jenkins: British Antarctic Survey, Cambridge, UK;
Marco Tedesco: Earth and Atmospheric Sciences, City College of New York, New York, New York, USA.
6. First satellite measurements of elusive sulfur compound in a volcanic plume
For the first time, satellites have
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American Geophysical Union